Water-absorbent materials such as superabsorbent materials including polysaccharides and superabsorbent polymers can be employed in different fields. For example, superabsorbent materials can be used in pet litter, household articles, sealing materials, humectants for agricultural products for soil conditioning, oil-drilling, anti-condensation coatings, water-storing materials in agriculture/horticulture, absorbent paper products, bandages and surgical pads, disposable sanitary products (such as diapers, incontinence articles, feminine hygiene products, airlaids and absorbent dressings), wound dressings, or as chemical absorbents.
Among known water absorbent materials, polysaccharides and polysaccharide mixtures have been widely used, alone or in conjunction with inorganic absorbent materials such as phyllosilicates. The more widely used polysaccharides are typically based on starch and/or cellulose, and the phyllosilicates can for example include bentonite.
Many processes for manufacturing such absorbent materials are known, and include for example granulation. A widely-used granulation process is wet granulation, including for example high shear mixture granulation, fluid bed granulation, extrusion-spheronization and spray drying. Wet granulation is known to have many advantages, such as increasing the density of the material, providing a better distribution of a compound of interest within the material compared to some other methods, reducing dust hazards, preventing segregation of powders and increasing the hydrophilicity of otherwise hydrophobic materials.
However, wet granulation also has many disadvantages. For example, granulation can be costly, as it often requires qualified personnel, large operation space and special equipment. Wet granulation also typically has a high energy requirement. Loss of material can occur during various stages of processing, and incompatibilities between the formulation components are typically aggravated during processing. More specifically, high shear mixture granulation can sometimes lead to mechanical degradation of the material.
Fluid bed granulation and extrusion-spheronization are often labor-intensive and time consuming, and have various other challenges.
There is therefore still a need for a process and apparatus for manufacturing water-absorbing materials that overcome at least one of the above-mentioned issues.